1. Field of the Invention
The present invention generally relates to the structure of infusion devices for infusing a predetermined reagent to lesion portions, for example, in body tissue.
2. Description of the Related Art
Conventionally, medical devices such as catheters have been introduced into tubular organs in the body such as blood vessels, the alimentary canal, and the ureters to perform various treatments, tests, and procedures, for example. More recently, treatment and procedures in which infusion devices such as infusion catheters have been used to infuse a predetermined liquid medicine into lesion portions in body tissues have been performed (see JP 2001-104487A and JP 2001-299927A).
That is, as is well known in the art, such infusion catheters are constituted by a tubular catheter member into which a needle-shaped tube member made of a narrow tube capable of conducting a predetermined reagent and having a sharp tip portion is inserted and disposed in such a manner that it can move in the axial direction of the catheter member. The catheter member of such an infusion catheter is then inserted into a blood vessel and pushed through the vessel until reaching the site of a lesion in a body tissue, at which point the needle-shaped tube member is moved longitudinally. The needle-shaped tube member is thereby passed through a tip opening or an aperture portion provided in the tube wall of the catheter member and the needle portion of the tip of the needle-shaped tube member is extruded to the outside to penetrate a lesion portion of the body tissue, and in this state a predetermined reagent is infused into the lesion portion through the needle-shaped tube member.
One type of an infusion device, such as an infusion catheter, has a structure in which at least three lumens are provided inside the tubular member, these being a needle-shaped tube member lumen into which the needle-shaped tube member is movably inserted, a guide wire lumen into which a guide wire is inserted, and a balloon lumen for conducting fluid for expanding a balloon that is attached to the outside of the tubular member.
In infusion devices having such a structure, it is not possible to keep the cross sectional area of the tubular member perpendicular to its axial direction from becoming large. For that reason, when using such infusion devices there is the concern that depending on the site in the body to which it is to be inserted it may be difficult to insert the tubular member into the body, even if the tubular member has an annular profile perpendicular to its axis such that it can be inserted into the body as smoothly as possible. Moreover, there is also a concern that the flow of blood may be arrested when the tubular member has been inserted into a blood vessel, for example.